Zim's war numbers are so much lower than Rendon. Zimmerman's offensive numbers look arguably a little better. Is that all because of fielding position?

Rendon plays elite 3rd base, and elite position. Zim plays a poor 1st base, which is not. Rendon also gets on base way more (.403 vs .351) And total offensive production goes to Rendon: wRc+ 141 for Rendon and 131 for Zim (100 is average)